Animal

1. Animal cell; structures
and functions
Lecture 1
Dr. Heba Metwaly
Biochemistry Lecturer

2.  Cell is the unit of living system
 Structurally ; it consists of an aggregate of
molecules that enabling the survival and growth
of the whole organism these molecules are cell
organelles
 Most organelles are membrane-enclosed
structures, Their membranes are composed of the
same components as plasma membranes that form
the outer boundaries of cells.
Overview

3.  Organelles do not float freely within the cytosol
but reside within the framework established by
the cytoskeleton
 Each organelle carries out a specific function.
Cytosol (liquid portion
of the cytoskeleton)
+ Cell organelles
Cytoplasm (composed of all materials contained
within plasma membrane boundaries)

4. Eukaryotic Cell
 Contain membrane-bound organelles.
Cell organelles are:
Nucleus Ribosomes
Endoplasmic reticulum
Golgi apparatus
Mitochondria
Lysosomes and peroxisomes
(Vesicles )

5. 1- Nucleus (plural = nuclei)
 All eukaryotic cells except mature
erythrocytes (red blood cells) contain a
nucleus.
 It is surrounded by nuclear envelope with
nuclear pores to permit transfer of
materials between the nucleus and the
cytosol.
 The interior of the nucleus contains the nucleoplasm; the fluid in which the
DNA(which carry our genetic information) are found.
 DNAcombine with specific protein
to form chromosome
 Within the nucleus there is a
suborganelle called the nucleolus.
The nucleolus is the site of ribosome
production.

6. Nucleus function
 During mitosis, chromosomes undergo
replication of their DNAand separation into
daughter chromosomes.
 DNA directs the protein biosynthesis inside the
cell

8. 2- Ribosomes
 Each ribosome has a large and a small
subunits
 They are composed of proteins
and ribosomal RNA(rRNA) with
40% being protein and 60%
rRNA.
 Ribosomes are found within the cytosol either
free or bound to the endoplasmic reticulum.
Function:
 Ribosomes are the cellular machinery for protein synthesis.

10. 3- Endoplasmic reticulum (ER)
ER appearing like a series of interconnected, flattened tubes
surround the nucleus
Two types :
A-Rough endoplasmic reticulum (rER).
Regions of ER where ribosomes are bound
to the outer membrane. Bound ribosomes
and the associated ER are involved in the
production and modification of proteins.
B- Smooth endoplasmic reticulum (sER) refers to the regions of
ER without attached ribosomes, its function is site for lipid
synthesis

11. 4-Golgi apparatus (Golgi complex)
 It appears as flat, stacked,
membranous sacs;
 Three regions are described within
Golgi complex
 The Cis: which is closest to ER
 The medial
 The Trans: which is near plasma
membrane
o Proteins from the rough ER enter at its cis face (entry face),
which is usually oriented toward the nucleus.
o They are then transported through the Golgi and exit from its
trans face (exit face).
o As they pass through the Golgi, proteins are modified and
sorted for transport to their destinations within the
cell.

12. Receiving protein synthesized in ribosomes (pack it and
sort it)
Performing modifications to it to make it well functioning
protein
Phosphorylations (addition of phosphate)
Proteolysis (enzyme-mediated breakdown of protein)
Glycosylations (addition of carbohydrate)
Secretion of cell products (protein) to outside the cell through
formation of vacuoles called secretory vesicles in which
secretory products are concentrated and transported their
destinations within the cell.
Function:

13. How proteins are transported within the cell.
• Proteins are manufactured at the ribosome and then
released into the rough ER.
• Proteins are transported outside of the cell
in form of vesicles that are emerged from
rough ER to the cis face of the Golgi
apparatus.
• They are modified and packaged into
secretory vesicles which migrate from the trans face
of the Golgi apparatus to other locations in the cell
or they fuse with the cell membrane, releasing their
contents to the external cellular environment.

14. 5- Lysosomes and peroxisomes (Vesicles )
Involved in digestion and detoxification
Lysosomes: are vesicles filled with potent enzymes have
an acidic internal pH, known as acid hydrolases that
breakdown macromolecules .
Peroxisomes: responsible for detoxification of
peroxides that damage cells

15.  lysosomes
1-Hydrolyze or break
macromolecules (proteins,
acids, carbohydrates and
down
nucleic
lipids)
that have reached the end of their
functional life. accumulation of non
function macromolecules is very
toxic to cells.
The clean up
crew
2- Degrade materials that taken up by the cell through
endocytosis or phagocytosis as accumulation of this material is
very toxic to cells.

17. Peroxisomes
Peroxisomes resemble lysosomes in size and in structure. They
have single membranes enclosing them and contain hydrolytic
enzymes.
Function : It helps in:
1- Break down of fatty acids and purines.
2- Detoxification of hydrogen peroxide (a toxic by-product of many
metabolic reactions).
3- Synthesis of myelin sheath around many neurons.
4- In liver cells, peroxisomes participate in cholesterol and bile acid
synthesis.

18. 6-Mitochondrion (plural = mitochondria)
that
lumen
folded structures called cristae
protrude into the mitochondrial
known as the mitochondrial matrix.
The mitochondrial membrane is double phospholipid bilayer
membranes that form the outer boundary of the organelle
The inner mitochondrial membrane forms

19. Function :
 Mitochondria is the power house of the cell
 Their unique membranes are used to generate ATP through
respiration (greatly increasing the energy yield from the
breakdown of carbohydrates and lipids).
 All enzymes of electron transport chain , energy liberation
and ATP formation are located in the inner membrane

20. The rough endoplasmic
reticulum has
located on it.
A. Lysosomes
B. cytosol
C. ribosomes
D. proteins
Peroxisomes helps in …….
A. generateATP
B.performing
modifications on protein
C. Synthesis of myelin
D. Synthesis of proteins

21. This organelle functions
in cellular respiration
A. lysosome
B. endoplasmic reticulum
C. mitochondrion
D. Golgi apparatus
Genetic material is
contained within the
of the cell.
A. Ribosomes
B. cytoplasm
C. nucleus
D. nucleolus

22. Which of the following
cells does not have a
nucleus?
A-Mature red blood cell.
B. Muscle cell.
C.Liver cell.
D. Heart muscle cell.
This organelle is
responsible for destroying
excess macromolecules
being engulfed by the cell
A. Lysosomes
B. mitochondrion
C. golgi apparatus
D. ribosomes

23. The direct the
protein biosynthesis
inside the cell
A. Mitochondrion
B. Golgi apparatus
C. nucleus
D. cell membrane
A membrane enclosed
intracellular structure
responsible for energy
A. Mitochondrion
B. Golgi apparatus
C. nucleus
D. cell membrane

24. Complete the missed data and
scientific name
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